This invention relates to a loose-leaf binder, and more particularly to a loose-leaf binder, such as a loose-leaf photo album or a loose-leaf file binder, having a plurality of pages neatly piled together, every abutting two of which are detachably and rotatably connected to each other by a plurality of axially aligned hinge members alternately formed along a pair of corresponding edges of said pages.
U.S. patent application Ser. No. 07/257,325 discloses a loose-leaf photo album the loose-leaf pages of which are capable of being easily and quickly engaged with each other by the insertion of the protruding pillars, which are provided at one part of the end portions of the hinge members alternately formed along the edge of each of the pages, and the concave knuckles of the remaining portion of the end portions of said hinge members via the axial slits formed on said remaining end portions of said hinge member. In addition, the engaging force between the adjacent hinge members of the loose-leaf photo album of application Ser. No. 07/257,325 can be increased by increasing the effective engaging length between said concave knuckle of said hinge member and the protruding pillar of the other connecting hinge member. However, because said protruding pillar, which is received in said concave knuckle, is merely clamped by the flexible wall of said concave knuckle, the engaging force between said concave knuckles and said protruding pillars may not be sufficient to prevent said loose-leaf pages, which are substantially thick and heavy, from being radially separated from one another via said axial slit in said hinge member.